Re: GnuTLS/NSS interop in Exim 4.80 RC

[Patrick Pelletier]

On May 22, 2012, at 1:38 AM, Janne Snabb wrote:

> Even if the hard
> limit in NSS is fixed quickly, this will be a burden for TLS server  
> side
> developers for many years to come.

It almost seems like a new TLS extension should be proposed, where the  
client can tell the server how many bits of DH it is willing to  
accept.  (Similar in spirit, although simpler than, the extension used  
to negotiate curves for elliptic curve.)  If the client sends the  
extension, then the server can know with confidence what size of DH  
params are acceptable.  If the client doesn't send the extension, the  
server can make a conservative assumption.  (Probably 2236 bits.)

Without such an extension, it seems like TLS servers that are  
concerned about interoperability (such as on the Web) will have to  
avoid exceeding 2236 bits for quite a long time.

--Patrick